The present invention relates to electrical engineering, particularly to the production of electrical machines and more specifically to a device for assembling a stator of a slotless electrical machine and a device to realize the given method.
It is generally known that in assembling conventional type stators with non-salient poles, first the stator lamination pack (non-wound stator) is made whose lamination steel has a yoke and a slot zones stamped together, then the stator pack receives conducting material either by winding wire directly in its slots (combined winding) or by inserting wire turns made separately (separate winding and placing) into slots to produce a wound stator.
The selection of the production process to make a wound stator, or the stator assembling process is determined by the design features of the geometry of a non-wound stator, windings and insulating parts.
In machines with combined operations of forming turns and placing them into stator pack slots, the wire feeding elements of the machine are moving in a certain trajectory whose perimeter differs from the perimeter of a turn of the winding. In the course of forming a turn, the tension of wire being wound varies (even a free loop may occur), and excessive axial and radial displacement of wire occurs when it slides over the surfaces of the turn forming components (templates, hooks), or in other words, a turn is obtained by winding wire over the curved surface of forming templates without any strict fixation.
This gives rise to the following disadvantages of the given method of stator assembling by a machine tool: relative elongation of wire (up to 10%) during the placement thereof, increased ohmic resistance of the winding, damaged insulating coating of winding wires, poor dependability of the machine equipment due to a complex trajectory of the operating motions of the wire feeding element which performs up to eight discrete motions, with two of them being performed at a distance of 300 and 400 mm, during a single cycle lasting about 0.1 sec.
A distinguishing feature of machines with separate operations of forming turns and placing them into the slots of the stator pack is winding a wire over the template of the given dimensions and configuration. A turn of the winding is made during this process under relatively stable conditions to acquire distinct geometric dimensions on the winding template. However, further operations of assembling turns into a winding and placing the latter into stator slots in value a substantial disadvantage because the process of inserting wire turns through the narrow entrance of the slot is accompanied with forcing the wire inward with a possible jamming of wires.
A somewhat more advanced method of separate forming and placing of windings into the slots of a stator pack is a method of their axial insertion according to which, coils made on the winding template are inserted singly into stator pack slots from the side of one of the stator ends.
However, none of the above methods of assembling the conventional type wound stator is suitable for assembling the stator of a slotless electrical machine. This is because the non-wound stator of a slotless electrical machine substantially differs in its design from that of the conventional type electrical machine.
The stator pack of a slotless machine has only a yoke zone, but no slot zone whatever. Therefore, assembling this type of stator includes the principally new processes, a creation of an active distributed layer of the stator and its cementing to the stator represents a multilayer winding comprising ferromagnetic elements between the layers of the winding whose geometry corresponds to the perimeter of the stator yoke bore. To obtain a rotating magnetic field in an electrical machine of this type, the active distributed layer is arranged of a plurality of elementary multilayer windings with ferromagnetic elements between layers, so called coil groups, which are interconnected (wired) into a common active distributed layer of the stator by means of an electric circuit.
As is known, the process of a manual assembling of a slotless electrical machine includes operations performed in a succession given below: coating the yoke surface with a cementing compound, successive introduction of each coil group into the yoke, successive positioning of each coil group in the corresponding position of the yoke, determined by a preliminary marking off and availability of corresponding fixing elements at this position. This assures the required relative positioning of all coil groups of the active distributed layer in the assembled machine; pressing each coil group to the yoke from their sides (commonly by means of a screw clamp) with a force sufficient for holding the coil group in the course of its cementing and for reliability of this process; curing during a time period needed for polymerization of the cementing compound; releasing the force of pressing the coil group to the yoke (by unscrewing and removing the screw clamp); and realizing all required electrical connections (wiring of electrical circuit).
It is obvious that the above described method of assembling the stator of the slotless electrical machines is so much labor intensive (especially the processes of successive introduction of coil groups into the inside of the yoke and their temporary securing on its surface by means of screw clamps until the polymerization process of cementing compound is finished) that mass production of electrical machines with a slotless stator on the basis of the above described method is believed to be impossible.
Attempts to mechanize assembling operations in the process succession adopted for the manual stator assembling method have not yielded the desired results because the functional layout of manipulators to perform the actions of placing and fixing coil groups on the surface of the stator yoke is too complicated, unreliable and low productive as a temporary fixing by manipulators of even two or three coil groups simultaneously is difficult due to a limited space in the stator yoke bore.
Therefore, a problem has arisen in developing a principally new assembling technique to meet the requirements of mass production of the slotless stators to the fullest extent.